1. Field of the Invention
The present invention relates to a cooling apparatus using boiling and condensing refrigerant, in which refrigerant is boiled by heat of a high temperature medium and is then condensed so as to radiate heat of the high temperature refrigerant, such as a cooling apparatus having a thermosyphon type heat exchanger.
2. Description of the Prior Art
Conventionally, heating elements such as electronic parts are occasionally housed in a closed housing. In this case, as a method for cooling the heating elements, there has been employed a method in which heat exchange is performed between air inside the housing and air outside the housing, because the outside air cannot be directly taken into the housing so as to ventilate the interior of the housing. As a method for obtaining a small number of parts and a large amount of heat movement, there has been known a method using heat pipes (in which a refrigerant is sealed) disposed so as to pass through a housing, as disclosed in JP-B2-2-3320.
In the heat pipe as disclosed in JP-B2-2-3320, the inside refrigerant is boiled by the high-temperature air in the housing, the refrigerant is condensed by the radiating portion disposed outside the housing so as to radiate the heat, and the condensed refrigerant again drops into the heat absorbing portion disposed within the housing.
However, in the heat pipe as disclosed in JP-B2-2-3320, vaporized refrigerant which has been boiled and rises and condensed refrigerant which has been condensed descends within the same pipe. Therefore, the flowing directions of the refrigerants are opposed to each other, and there may cause a problem in that the entire refrigerant does not circulate efficiently.
In view of the foregoing, there has been also known a cooling apparatus using boiling and condensing refrigerant in which the heat can be efficiently radiated by circulating the refrigerant, as in JP-U-62-162847. According to the cooling apparatus disclosed in JP-U-62-162847, a heating element is secured to a refrigerant tank, heat generated by the heating element is absorbed by a refrigerant sealed in the refrigerant tank, the refrigerant boiled and vaporized by the heat absorption is condensed and liquefied by a radiator disposed on the refrigerant tank, and the condensed and liquefied refrigerant is returned to the refrigerant tank through a refrigerant return pipe inserted into the refrigerant tank.
However, in the cooling apparatus disclosed in JP-U-62-162847, since the refrigerant return pipe for returning the refrigerant condensed by the radiator to the refrigerant tank is inserted into the refrigerant, the refrigerant may be heated within the refrigerant return pipe before returning back into the refrigerant tank, the buoyancy in the upward direction is exerted on the refrigerant, and the refrigerant does not return back into the refrigerant tank efficiently. As a result, there occurs a problem in that the refrigerant circulates slowly and the radiating performance deteriorates.
Further, in the case where a passage for communicating between the refrigerant tank and the radiator is cooled when the refrigerant boiled and vaporized from the refrigerant tank rises to the upper radiator, the boiled and vaporized refrigerant is condensed in the passage and drops down before moving to the radiator. As a result, there occurs a problem in that the refrigerant circulates slowly and the radiating performance deteriorates.
Further, by the deterioration of the radiating characteristics, the cooling apparatus becomes large-sized.
The present invention has been accomplished on the basis of the aforementioned circumstances. A first object of the present invention is to downsize the cooling apparatus by employing a new construction.
A second object of the present invention is to provide a cooling apparatus, capable of preventing the circulation of the refrigerant from being impeded.
A third object of the present invention is to provide a cooling apparatus, having a low-temperature-side communication pipe for returning refrigerant condensed by a radiator to a refrigerant tank and capable of preventing an occurrence of an ascending force of the condensed refrigerant within the low-temperature-side communication pipe when the heating of the low-temperature-side communication pipe is heated.
A fourth object of the present invention is to provide a cooling apparatus, having a high-temperature-side communication pipe for sending refrigerant boiled by a refrigerant tank to a radiator and capable of preventing vaporized refrigerant from being condensed within the high-temperature-side communication pipe when the cooling of the high-temperature-side communication pipe is cooled.